Gift deed of flat to Sister

Hello, I want to Gift deed my flat (Jointly holded by ME, My wife, My Father, My Mother) to my Sister. Flat was purchased in August 2014 with home loan. For F.Y. 2014-2015 I had taken Home loan benefit. For F.Y. 2015-2016 I had taken Home loan benefit. In the month of Feb 2016 we have cleared home loan by my father part PF withdrawal. Currently Flat is not mortgaged. My Queries are: 1. Since flat is jointly hold by Me, My father, My mother and my WIFE; is gift DEED allowed in this case because my wife is not directly in blood relation with my wife. Is any clause mentioned in law is against such gift deed transfer. 2.With consideration of short term capital gain or long term capital gain, when i can gift deed such property i) 3 years After completion of Home Loan or ii) 3 years After purchase of Home 3.As per new law now for gift deed it can be done with 500rs stamp paper.....please confirm. or do i need to register in registar office.Stamp duty (which is near about 5.5~6%) is removed by maharashtra government. Please confirm